ID_F_WAIT_BUSY
d->d_flags |= ID_F_WAIT_BUSY;
#define ID_F_KEEPALIVE_MASK (ID_F_DIRECT | ID_F_BUSY | ID_F_WAIT_BUSY)
if (d->d_flags & ID_F_WAIT_BUSY) {
d->d_flags &= ~ID_F_WAIT_BUSY;